code: def _diff_conditional(expr, base_scalar, coeff_1, coeff_2):
      """
      First re-expresses expr in the system that base_scalar belongs to.
      If base_scalar appears in the re-expressed form, differentiates
      it wrt base_scalar.
      Else, returns 0
      """
      from sympy.vector.functions import express
  
      new_expr = express(expr, base_scalar.system, variables=True)
      arg = coeff_1 * coeff_2 * new_expr
      return Derivative(arg, base_scalar) if arg else S.Zero
  
imports: import collections
  from sympy.core.expr import Expr
  from sympy.core import sympify, S, preorder_traversal
  from sympy.vector.coordsysrect import CoordSys3D
  from sympy.vector.vector import Vector, VectorMul, VectorAdd, Cross, Dot
  from sympy.core.function import Derivative
  from sympy.core.add import Add
  from sympy.core.mul import Mul
label_desc: Use image node_id 6 for calling a global function with example usage: _diff_conditional(expr, base_scalar, coeff_1, coeff_2) and returns: unknown